The present invention relates to a multi-functional laser printer using a double-structured hologram disk, and more particularly to a multi-functional laser printer which is capable of performing a function of forming a picture on a photosensitive drum as well as a manuscript reading-out function.
Generally used laser printer is structured with a laser beam scanning unit, a computer for controlling the laser beam scanning unit so as a laser beam to be outputted according to the information to be printed, and a printing unit for forming a picture on a photosensitive drum and executing a printing operation in accordance with the laser beam being applied from the laser beam scanning unit thereto.
A typical type of such a conventional laser printer is illustrated in FIGS. 1 and 2.
In FIGS. 1 and 2, reference numeral 1 denotes a laser beam scanning unit, 10 is a printing unit, and 23 is a computer. The laser beam scanning unit 1 comprises a laser 2 which generates a laser beam (l), a collimator 3 which changes the laser beam (l) into a parallel light, a cylindrical lens 4 which concentrates the parallel light from the collimator 3 toward a rotary polyhedric mirror 5, compensating lenses 7 and 8 which compensate the laser beam reflected from the rotary polyhedric mirror 5 so as to be formed as a picture accurately on a photosensitive drum 11, and a reflective mirror 9 which deflects the laser beam from the compensating lenses 7 and 8 toward the photosensitive drum 11.
The rotary polyhedric mirror 5 is driven by a drive motor 6, and each of the compensating lenses 7 and 8 has at least one toric surface on one side surface thereof.
The printing unit 10 comprises a photosensitive drum 11 on which the laser beam from the laser beam scanning unit 1 is formed as a picture, an electrifier 12, a developer 13, a transfer printer 14, a separator 15, an electricity remover 16, a fixing heater 17, a cleaner 18, and means for feeding, conveying and discharging papers. Said means for feeding, conveying and discharging papers comprises a cassette 19, paper feeding rollers 20, paper discharging rollers 21, and a paper discharging tray 22.
In such a conventional laser printer, the laser 2 emits a laser beam 1 while being turned on or off in response to the picture signal received from the computer 23, and the emitted laser beam (l) is converted into a parallel light by the collimator 3 and then converged on the mirror surface of the rotary polyhedric mirror 5 by the cylindrical lens 4.
The laser beam (l) converged to said rotary polyhedric mirror 5 is reflected at various angles according as said rotary polyhedric mirror 5 is rotated by the driving force of the drive motor 6, and deflected by the reflective mirror 9 after passing through the compensating lenses 7 and 8 and then converged on the photosensitive drum 11.
The compensating lenses 7 and 8 compensate the focal locus of the laser beam (l) from a curved line to a straight line when the laser beam (l) is converged and scanned on the photosensitive drum 11 and also compensate the laser beam (l) being moved slightly perpendicular to the scanning plane due to an inclination of the mirror surface of the rotary polyhedric mirror 5 or a vibration of the mirror surface when the rotary polyhedric mirror 5 turns.
After the laser beam (l) is thus focused on the photosensitive drum 11, the printing operation is executed by the well known general printing process.
However, such a conventional laser print is merely capable of performing a simple operation for forming a picture on a photosensitive drum. Moreover, since the compensating lenses require at least one toric surface on one surface thereof in order to compensate the focal locus from a curved line into a straight line the laser beam must be moved slightly in the direction perpendicular to the scanning surface. As a result, in the increase of cost.